px4 运行mavros仿真

安装好mavros后，需要添加一下px4源码的路径，否则不能使用px4的launch文件

gedit .bashrc

如果Firmware在home目录下，则添加如下

source /opt/ros/melodic/setup.bash
#source ~/catkin_ws/devel/setup.bash
source ~/01sousuo/Firmware/Tools/setup_gazebo.bash ~/01sousuo/Firmware/ ~/01sousuo/Firmware/build/px4_sitl_default
export ROS_PACKAGE_PATH=$ROS_PACKAGE_PATH:~/01sousuo/Firmware
export ROS_PACKAGE_PATH=$ROS_PACKAGE_PATH:~/01sousuo/Firmware/Tools/sitl_gazebo

保存后 source .bashrc

然后运行roslaunch px4 ​​mavros_posix_sitl.launch​​

连接成功的话会弹出无人机的id等信息

如果是二进制安装的mavros

则在～/.bashrc中添加

​​source /opt/ros/melodic/setup.bash​​

如果出现ERROR: cannot launch node of type [mavros/mavros_node]错误，则把catkin_ws里的内容删掉重新编译一下工作空间。

或者把原来的catkin_ws删掉

重新创建

mkdir -p Offboard_ws/src

cd Offboard_ws/src

catkin_create_pkg offboard roscpp std_msgs geometry_msgs mavros_msgs

cd offboard/src
gedit offboard_node.cpp

复制以下代码进去

#include <ros/ros.h>
#include <geometry_msgs/PoseStamped.h>
#include <mavros_msgs/CommandBool.h>
#include <mavros_msgs/SetMode.h>
#include <mavros_msgs/State.h>

mavros_msgs::State current_state;
void state_cb(const mavros_msgs::State::ConstPtr& msg){
    current_state = *msg;
}

int main(int argc, char **argv)
{
    ros::init(argc, argv, "offb_node");
    ros::NodeHandle nh;

    ros::Subscriber state_sub = nh.subscribe<mavros_msgs::State>
            ("mavros/state", 10, state_cb);
    ros::Publisher local_pos_pub = nh.advertise<geometry_msgs::PoseStamped>
            ("mavros/setpoint_position/local", 10);
    ros::ServiceClient arming_client = nh.serviceClient<mavros_msgs::CommandBool>
            ("mavros/cmd/arming");
    ros::ServiceClient set_mode_client = nh.serviceClient<mavros_msgs::SetMode>
            ("mavros/set_mode");

    //the setpoint publishing rate MUST be faster than 2Hz
    ros::Rate rate(20.0);

    // wait for FCU connection
    while(ros::ok() && !current_state.connected){
        ros::spinOnce();
        rate.sleep();
    }

    geometry_msgs::PoseStamped pose;
    pose.pose.position.x = 0;
    pose.pose.position.y = 0;
    pose.pose.position.z = 2;

    //send a few setpoints before starting
    for(int i = 100; ros::ok() && i > 0; --i){
        local_pos_pub.publish(pose);
        ros::spinOnce();
        rate.sleep();
    }

    mavros_msgs::SetMode offb_set_mode;
    offb_set_mode.request.custom_mode = "OFFBOARD";

    mavros_msgs::CommandBool arm_cmd;
    arm_cmd.request.value = true;

    ros::Time last_request = ros::Time::now();

    while(ros::ok()){
        if( current_state.mode != "OFFBOARD" &&
            (ros::Time::now() - last_request > ros::Duration(5.0))){
            if( set_mode_client.call(offb_set_mode) &&
                offb_set_mode.response.mode_sent){
                ROS_INFO("Offboard enabled");
            }
            last_request = ros::Time::now();
        } else {
            if( !current_state.armed &&
                (ros::Time::now() - last_request > ros::Duration(5.0))){
                if( arming_client.call(arm_cmd) &&
                    arm_cmd.response.success){
                    ROS_INFO("Vehicle armed");
                }
                last_request = ros::Time::now();
            }
        }

        local_pos_pub.publish(pose);

        ros::spinOnce();
        rate.sleep();
    }

    return 0;
}

继续执行

cd …

gedit CMakeLists.txt

在最末尾添加如下内容后保存退出

add_executable(${PROJECT_NAME}_node src/offboard_node.cpp)
target_link_libraries(${PROJECT_NAME}_node
  ${catkin_LIBRARIES})

然后编译

cd ~/Offboard_ws
catkin_make

添加环境变量

echo "source ~/Offboard_ws/devel/setup.bash" >> ~/.bashrc

然后先

roslaunch px4 mavros_posix_sitl.launch

再启动offboard节点,正常的话无人机会起飞至2米

注意export 开头的环境变量必须放在最下面，source开头的如果放在最下的话，会导致无法使用roslaunch px4 mavros_posix_sitl.launch，以及直接启动launch文件是提示找不到路径